In a world with personalized advertising, you can avoid those ads forever. In mediums without personalized advertising, you can't watch a sporting event without seeing a beer ad.
Then again, personalized exclusion opens the door to many types of discrimination - like not showing job or housing ads to people with certain traits.
All that to say, the tech can be used for both good and evil. It needs to be managed by regulation, and not by technical feasibility.
The regulation people want, such as even stronger GDPR, is effectively almost a technical feasibility block on these things. Any other attempt is always going to be behind the technology curve and thus significantly less useful. Moreover politicians will add in exceptions for their top donors and friends. This is harder is regulation that doesn't get into deep weeds.
Alas, this is not how the real world works. Everyone on the advertising side has an incentive to exploit my weak sides, so I can't trust advertisers in general. And so they spy on me, and I'm desperately trying to protect myself.
Your hypothetical reality is an unstable equilibrium. Our actual reality is a stable one. So even if, by some miracle, the stars aligned and the hypothetical suddenly became real, it would very quickly degenerate into our current reality. "In paradise, the first one to pick up a stone becomes Genghis Khan", and all that.
So, in conclusion, adtech industry needs to be burned out by regulatory means like the cancer it is, until what remains can be reshaped into a construct that provides value to the society.